1. Field of the Invention
The present invention relates to a lifting mechanism of a vehicle seat to be provided to the vehicle seat so as to adjust a seating height position of the vehicle seat.
2. Description of the Related Art
A vehicle such as automobile is provided with a vehicle seat on which a passenger sits. The vehicle seat has a seat cushion that is a space on which the passenger sits and a seatback that becomes a backrest when the passenger sits on the seat cushion. A vehicle seat has been known, which enables a passenger to adjust a seating front-back position or seating height position. In such a vehicle seat, a lifting mechanism for adjusting a seating height position of the seat in a vertical direction is provided. A lifting mechanism for adjusting a seating height position in a vertical direction has been known, which is provided on a member (hereinafter, referred to as ‘floor-side member’) fixed to a vehicle floor, for example, and thus supports a seating-side configuring part for seating such as seat cushion and seatback. The lifting mechanism supports not only the seating-side configuring part but also a weight of a passenger sitting on the seat cushion.
The vehicle such as automobile, to which the vehicle seat is provided may collide from a front side (hereinafter, referred to as ‘front side collision of a vehicle’) or from a rear side (hereinafter, referred to as ‘rear side collision of a vehicle’). In case of the front or rear side collision of a vehicle, the vehicle seat receives unexpected load toward a front side or rear side due to inertia force. Therefore, a lifting mechanism is provided with a rotation stopper mechanism that supports inclination of the seating-side configuring part in the load direction even when the accidental load is applied (for example, see JP 2009-208737A).
The rotation stopper mechanism, which supports the unexpected load that is applied at the time of the front or rear side collision of a vehicle, is preferably configured by the small number of parts, from a manufacturing point of view. Therefore, there is a need to reinforce the respective constitutional parts so as to sufficiently bear the unexpected load even when the rotation stopper mechanism is configured by the small number of parts.
However, a link that configures the rotation stopper mechanism for the front and rear side collisions of a vehicle, which is described in JP 2009-208737A, is formed with a long hole that configures a part of the rotation stopper mechanism for the rear side collision of a vehicle. A contact part that configures a part of the rotation stopper mechanism for the rear side collision of a vehicle is provided adjacent to the long hole. Here, the contact part is a part to which a stopper part of the floor-side member is contacted so as to restrain rotation of the link at the time of the front side collision of a vehicle. However, the long hole close to the contact part has such a shape that a metal thickness is removed (i.e., having no metal thickness). Accordingly, when load is applied to the contact part due to the front side collision of a vehicle, the long hole close to the contact part cannot bear the load and is thus deformed, so that the seating-side configuring part may be inclined.